Respirators are well known to those skilled in the art. Thus, by way of illustration, one such respirator is described in U.S. Pat. No. 4,215,681 of Zalkin et al. The respirator of this patent is comprised of a reciprocating linear electric motor-compressor having a gas intake orifice connected to atmosphere, a piston, a spring acting on the piston, and an electromagnet for moving the piston against the action of the spring to supply compressed gas to a mask via a discharge orifice. In this device, a thyristor pulse generator is controlled by a clock to provide pulses to the electromagnet to define insufflation time; and the compressor operates only during the insufflation time.
The respiratory apparatus of the Zalkin et al. patent only is capable of providing intermediate positive pressure ventilation, i.e., a pulsed output provided at a specified frequency. However, it is often desirable for a respiratory apparatus to be able to provide an irregular output which is synchronized with a patient's breathing (which output is often referred to as "synchronized intermittent mandatory ventilation" ); the apparatus of the Zalkin patent is not capable of providing such irregular, synchronized output.
In certain situations, it is desirable for an operator to be able to manually control the output of a respiratory device, to provide a "continuous positive airway pressure manual cycle". The apparatus of the Zalkin et al. patent is not capable of such manual control and cannot provide such cycle.
Although Zalkin et al. intended to provide "...a respirator of particularly simple design..."(see column 1), in fact their device is relatively expensive and cumbersome; it does not appear that the Zalkin et al. device is portable. Because of these requirements, it is not believed that the Zalkin et al. apparatus is of the desired "...particularly simple design...."
In 1985, in U.S. Pat. No. 4,493,614, another respiratory device was disclosed by Raymond D. Chu et al. Although a pump intended for use in portable ventilators is disclosed in this patent, there is no disclosure of a device which is capable of providing either synchronized intermediate mandatory ventilation or the continuous positive airway pressure manual cycle described above.
It is an object of this invention to provide a portable ventilating device which can, in emergency situations, be used in place of mouth-to-mouth resuscitation ("CPR") and thus minimize the risk of spreading infectious disease.
It is yet another object of this invention to provide a portable ventilating device which does not require a separate source of compressed air.
It is an object of this invention to provide a portable ventilating device which is relatively inexpensive and lightweight.
It is another object of this invention to provide a portable ventilating device which is contains electromechanical means capable of furnishing intermittent positive pressure ventilation, and synchronized intermittent mandatory ventilation, and continuous positive airway pressure.
It is yet another object of this invention to provide a portable ventilating device which is relatively durable and has relatively few moving parts.